Pesticides and Pest Control

The statement that “the green revolution has also created havoc by exterminating the species of useful parasites and viruses” means

Directions: Read the passage and answer the question that follows.

No doubt, the ‘green revolution’ has led to self - sufficiency in food production but it has also brought with it the formidable problem of poisoning of food grains and other eatables. This is caused by excessive use of chemicals on crops and pesticide residues. It has also created havoc by exterminating the species of useful parasites and viruses which keep pests under control. Scientists are now worried about the resurgence of such formidable pests in menacing proportions which seem to undermine all that they have achieved in agricultural production.

Why is the prolonged usage of allethrin in the insect repellents harmful?

Directions: Read the passage and answer the following question.

Many personal insect repellents contain DEET (N, N-diethyl-m-tolu-amide), which is a mosquito repellent but also a skin irritant as well as a neurotoxin. If you have to use a repellent containing DEET, choose one with minimal levels of the chemical, preferably less than 10 per cent, and use it only when you really need to, for example where mosquito-borne diseases, such as malaria, are prevalent.
Avoid repeated use and applying the repellent to broken skin. Be particularly cautious with children.
Look for DEET - free repellents containing herbal essential oils, such as citronella, lavender, lemon grass, pennyroyal and peppermint. You will need to apply these more often and they may not be as effective as DEET - based types, but they are safer for long - term use.
Many mosquito repellents contain allethrin, a synthetic pyrethroid that is a central nervous system stimulant. Prolonged use should be avoided, especially by children. Use allethrin - based products only outdoors. Safer alternatives are to burn a citronella candle outdoors and use screens and nets indoors.

Allethrin’s prolonged usage is especially damaging to

Directions: Read the passage and answer the following question.

Many personal insect repellents contain DEET (N, N-diethyl-m-tolu-amide), which is a mosquito repellent but also a skin irritant as well as a neurotoxin. If you have to use a repellent containing DEET, choose one with minimal levels of the chemical, preferably less than 10 per cent, and use it only when you really need to, for example where mosquito-borne diseases, such as malaria, are prevalent.
Avoid repeated use and applying the repellent to broken skin. Be particularly cautious with children.
Look for DEET - free repellents containing herbal essential oils, such as citronella, lavender, lemon grass, pennyroyal and peppermint. You will need to apply these more often and they may not be as effective as DEET - based types, but they are safer for long - term use.
Many mosquito repellents contain allethrin, a synthetic pyrethroid that is a central nervous system stimulant. Prolonged use should be avoided, especially by children. Use allethrin - based products only outdoors. Safer alternatives are to burn a citronella candle outdoors and use screens and nets indoors.

Which is a better alternative to DEET?

Directions: Read the passage and answer the following question.

Many personal insect repellents contain DEET (N, N-diethyl-m-tolu-amide), which is a mosquito repellent but also a skin irritant as well as a neurotoxin. If you have to use a repellent containing DEET, choose one with minimal levels of the chemical, preferably less than 10 per cent, and use it only when you really need to, for example where mosquito-borne diseases, such as malaria, are prevalent.
Avoid repeated use and applying the repellent to broken skin. Be particularly cautious with children.
Look for DEET - free repellents containing herbal essential oils, such as citronella, lavender, lemon grass, pennyroyal and peppermint. You will need to apply these more often and they may not be as effective as DEET - based types, but they are safer for long - term use.
Many mosquito repellents contain allethrin, a synthetic pyrethroid that is a central nervous system stimulant. Prolonged use should be avoided, especially by children. Use allethrin - based products only outdoors. Safer alternatives are to burn a citronella candle outdoors and use screens and nets indoors.

We can protect ourselves from trouble by

Directions: Read the following passage and answer the related question.

The stability of the system of living creatures is linked with the natural food chain. Plants produce carbohydrates and protein and are eaten by herbivorous animals. We know the importance of all the organisms involved in this predator-prey food chain. By introducing toxic chemicals, which will be passed on to man through the food chain, or by destroying any of the species, we are only creating trouble for ourselves.

An interesting example is the ladybird beetle brought from Australia to California to prevent cottony-cushion scale insects infecting citrus plants there. The beetle ate up the insects and the situation improved. But recently DDT sprayed to control the other pests in the citrus trees affected the beetle and the cottony-cushion scales are dangerously active again.

To save crops, we kill sparrows and the insects multiply. It is said that one of the European countries which did this had to import sparrows to control the insects. Kill all the snakes in India because they are dangerous, and tomorrow you may have to import snakes to kill rats.